1. Field of the Invention
The present invention relates to automated communications with touchscreen devices, e.g., to touchscreen devices using capacitive sensing.
2. Description of Related Art
Personal digital assistants (or PDAs) are generally known, see e.g., Wikipedia contributors, “Personal digital assistant.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 18 May 2011, Web. 10 Jun. 2011. PDAs are mobile devices offering personal information manager capabilities. Typically, a PDA has an electronic visual display (or display for short) and more generally various user interfaces. Newer products also have audio capabilities and can be used as mobile phones (“smartphones”) or portable media players. Today, almost all PDAs are smartphones. Also, most PDAs have the ability to connect to the Internet and include a web browser. In fact, many PDAs can access the Internet, intranets or extranets via Wi-Fi or Wireless Wide Area Networks.
Many PDAs use touchscreen technology. A touchscreen (or touch-sensitive display) is an electronic display sensing the location of a touch event within the display area. Usually, touching the display is done with a finger. Touchscreens can also sense passive objects such as a stylus. Touchscreens are typically used in devices such as all-in-one computers, tablet computers, PDAs and smartphones, see e.g., Wikipedia contributors. “Touchscreen.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 6 Jun 2011. Web. 10 Jun 2011. There are a variety of touchscreen technologies, e.g., resistive, capacitive, infrared, etc.
Capacitive sensing is perhaps the most used technology for PDAs. A capacitive touchscreen panel includes an insulator such as glass, coated with a transparent conductor, e.g., indium tin oxide. Touching the surface of the screen with a conductor (human body is also an electrical conductor) results in a distortion of the electrostatic field of the screen, which can be measured as a change in capacitance.
Security problems with PDAs (just like PCs) make them unsuitable for many functions since data entered by users can be manipulated or copied by an attacker. For example, transactions can be changed to send money to unwanted recipients or to order unwanted goods, or user credentials can be copied providing attackers with access to systems such as those used for Internet banking.
Beyond PDAs, touch-sensitive displays become increasingly prevalent in many electronic devices ranging from smartphones, tablet PCs or Laptops to special purpose devices such as ATM machines. While displays primarily act as human interface devices they can also be used for one-way short-range wireless data communication between two devices. For example, in case of the so-called flicker code application where one device encodes data within a flickering image that is shown on its display and a second device equipped with a photodetector (i.e., having light sensing elements) can then receive and decode this data when such elements are placed close to the flickering image, see e.g. http://www.axsionics.ch/tce/frame/main/422.htm and http://www.reiner-sct.com/index.php?option=content&task=view&id=162.